1. Field of the Invention
The present invention relates to an apparatus for measuring a picture and a lifetime of a display panel such as LCD, TFT-LCD and OLED and, more particularly, to an apparatus for measuring a picture and a lifetime of a display panel capable of rapidly and precisely measuring characteristics concerned with brightness reduction and a lifetime.
2. Discussion of Related Art
As information and communications industry is advanced, a mobile phone, an audio, a monitor, a digital still camera, a large-screen TV and so on have been widely used, and therefore, various display panels such as a liquid crystal display (LCD), a thin film transistor liquid crystal display (TFT-LCD), and an organic light emitting diode (OLED) have been developed and produced.
However, since these display panels have also disadvantages, while having various advantages, various efforts has been attempted in order to improve these disadvantages.
For example, the OLED has various advantages such as emissive characteristics, high efficiency, wide viewing angle, rapid response speed, low power consumption and so on, however, it has also disadvantages such as device deterioration due to reaction with moisture and oxygen in atmosphere, lifetime reduction due to oxidation of electrodes, and so on.
In order to solve these problems, it is required to find and observe the problems in a developing process of the display panel to improve various characteristics and lifetime. For this, it is necessary to provide an apparatus for observing the display panel.
A. B. Chwang et al, and K, Yamashita et al had measured the relationship between current, voltage and brightness of devices using a brightness meter adopting a driving theory of an organic light emitting display or measurement apparatuses adopting a photo diode, and had observed the lifetime of the encapsulated devices therethrough (A. B. Chwang et al, Applied Physics Letters 83 (2003), p. 413; and K, Yamashita et al Journal of Physics D: Applied Physics, 34, (2001), p. 740).
In addition, Korean Patent Application No. 10-2001-0075499 discloses a method of measuring brightness variations depending on variations of current and voltage using a brightness meter capable of moving in directions of x, y and z axes.
However, these methods cannot observe in detail an entire surface of the display panel since the display panel is partially measured using optical instruments such as a brightness meter or a photo diode, and it is difficult to analyze in a short amount of time since the optical instruments should intermittently measure while scanning along x-axis or y-axis in order to observe the characteristics of the large-screen display panel. In addition, since it is impossible to discriminate and analyze in detail causes seriously affecting the lifetime of the device such as dark spots generated and grown in the display panel, edge degradation of an emission surface, variations of uniformity depending on variations of electric power and so forth, it is difficult to find methods capable of improving the lifetime of the device.